Obama defends surveillance programs

US President argued that an NSA program to sweep up telephone numbers, data on calls had been authorised by Congress.

SAN JOSE: US President Barack Obama mounted a staunch defense Friday of just exposed spy agency surveillance programs, telling Americans "nobody is listening to your telephone calls."

Obama also said there was a tradeoff to be made between national security and people's privacy, though he said it was right that the exact balance between the two should be publicly debated.

He argued that a National Security Agency (NSA) program to sweep up telephone numbers and data on calls -- but not conversations themselves -- had been repeatedly authorized by Congress and were overseen by a special court.

He also hit out what he said was the "hype" over the programs revealed in a dizzying 24 hours of revelations in newspaper reports over the last two days.

"Nobody is listening to your telephone calls. That's not what this program's about," Obama said, noting that intelligence agents who did want to listen to content of calls had to go back to a federal judge for authorization.

Obama also said that a separate program, known as PRISM, targeting foreign terrorists and tapping into the servers of nine top Internet firms was not aimed at anybody in the United States.

"This does not apply to US citizens. And it does not apply to people living in the United States," Obama said.

Civil liberties and privacy groups have raised alarm at the two programs, reported by the Guardian and Washington Post newspapers, warning they are "Orwellian" and could be unconstitutional.

Obama said he welcomed the debate, but warned that the programs had previously been kept under wraps to avoid tipping off America's enemies.

"I think it's important to recognize that you can't have 100 percent security and also then have 100 percent privacy and zero inconvenience. We're going to have to make some choices as a society."